1. Field of the Invention
The present invention relates to a radio resource allocation method that controls allocation of up/down link radio resources to mobile stations linked to a base station for use in mobile communications between the mobile stations through the base station. Further, the present invention relates to a base station that uses the radio resource allocation method for mobile communications between mobile stations through the base station.
2. Description of the Related Art
With the advent of recent multimedia services, mobile communication systems have become to utilize not only the existing voice communications but also non-voice communications including data and image transmissions. In the non-voice communications, the amount of the uplink traffic and the amount of the downlink traffic are often diversified in a non-symmetrical manner. Moreover, the non-voice communications are likely to undergo variations of the amounts of the up/downlink traffic that are larger than those in the voice communications.
In order to resolve the above problems, it is desirable that radio resources, which must be allocated to mobile stations linked to the base station of concern, be shared for both the uplink and the downlink related to the base station of concern. Radio resources with respect to the present invention mean the radio channels or channel timeslots that have to be allocated to and shared by the respective links between the mobile stations and the base station of concern, namely, both the uplinks between the respective mobile stations and the base station and the downlinks between the base station and the respective mobile stations.
In a conventional radio resource allocation method, the radio resources are allocated to the uplinks and the downlinks based solely on the comparison of the amount of the uplink traffic and the amount of the downlink traffic in the cell site of the base station of concern. According to the conventional method, when the uplink traffic within the cell site is larger in amount than the downlink traffic there, the base station allocates a larger amount of radio resources to the uplinks than to the downlinks. On the other hand, when the downlink traffic in the cell site of the base station is larger in amount than the uplink traffic there, the base station allocates a larger amount of radio resources to the downlinks than to the uplinks.
However, according to the above-described conventional method, there is the possibility that the radio resources allocated to the links in the cell site of the base station of concern are being used in the radio resources allocated to the links in the cell site of a neighboring base station located adjacent to the base station of concern. In such a case, the interference of the radio resources between the base station of concern and the neighboring base station takes place, and the characteristics of the data transmission in both the cell sites of the base stations will deteriorate.
When the direction of the link data transmission in the cell site of the base station of concern is opposite to the direction of the link data transmission in the cell site of the neighboring base station in the case of allocating the radio resources to both the uplinks and the downlinks, the interference of the radio resources between the base stations or between the mobile stations is likely to take place. Hence, in the case of allocating the radio resources to both the uplinks and the downlinks based solely on the comparison of the uplink and downlink traffic amounts in the cell site of the base station of concern, the interference of the radio resources between the base stations or between the mobile stations is likely to take place, and it will cause the quality of the mobile communications to deteriorate. Further, the interference of the radio resources will cause an increase of the number of retransmissions and an increase of the delay of data transmission, and therefore the efficiency of utilization of the radio resources of the entire mobile communication system will be considerably lowered.